That depends on how far you’d like to go to avoid them. If you’d prefer to stay at home tonight, then find an isolated room deep in the house. A basement would work best, but in a pinch, try to put her into the furthest bedroom from the fireworks. If you have a fan or white noise machine, place them in the room and turn them on to help dampen the sound. A TV tuned to static will also do. Give her plenty of water and treats, and stay with her for as long as you’re willing. Only sedate her if this doesn’t work.
If, however, you’re able and willing to travel tonight, consider spending the holiday in a remote area or in a town that isn’t hosting fireworks. Sometimes, it’s just as fun to hold a bonfire on a remote beach as it is to be anywhere near a fireworks display.
If all else fails and you have more than one pokémon, you may consider using the PC system as well, but this is (understandably) a last resort.